1. Field of Invention
The present invention relates to a tie-down device and, more particularly, to a tie-down device equipped with a speed-increasing gearbox.
2. Related Prior Art
As disclosed in U.S. Pat. Nos. 5,611,520, 7,100,902 and 8,172,203, a tie-down device includes a frame, two axles and a knob. The frame includes two separate walls extending from a base. The axles are supported on the walls. The knob is connected to an end of one of the axles that extends beyond one of the walls. The knob is operable to wind a strap onto the axle that is connected thereto. However, the winding of the strap onto the axle is troublesome and slow.
As disclosed in U.S. Pat. No. 6,609,275, a tie-down device includes a frame, an axle, a reel and a coil spring. The axle is non-rotationally supported on the frame. The reel is rotationally provided around the axle. The coil spring includes an end connected to the axle and another end connected to the reel. The coil spring is loaded as a strap is unwound from the reel. The strap can be wound onto the reel by the coil spring. The wind of the strap onto the reel is automatic. However, the diameter of the coil spring is large as the strap is long. That is, a large coil spring requires a lot of steel which is heavy and expensive.
Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in prior art.